Repair of Circulating Water Pump (CWP) Inspection-Finding Parts at PLN IP UBP Suralaya

Sinar Sakti Matra Nusantara (SSMN) carried out repair work on Circulating Water Pump (CWP) components identified by inspection findings at PT PLN Indonesia Power's Banten 1 Suralaya Generation Business Unit. The work covered the repair of a range of critical pump components — impeller, diffuser, lower shaft, guide vane, stage case, and inner column.

The programme ran end to end: incoming inspection and the drafting of a Work Procedure Specification (WPS) first, then repair, machining, welding, and centring, and finally Non-Destructive Testing (NDT) to confirm the quality of the finished repairs.

Impeller Repair

Inspection found several conditions on the impeller: blade fracture, blade erosion, cracking, deformed and dented blades, over-clearance between the impeller surface and the stage case, and wear on two threaded holes. To restore the component, SSMN repaired the blades, which included joining and adding material in the damaged areas. The blade surfaces were also given a ceramic coating underneath and an epoxy coating on top. Where dimensions had changed, build-up welding and recontouring were carried out and then machining on a lathe; the worn threaded holes were repaired by re-tapping.

After repair, NDT was performed using Penetrant Testing (PT) and Magnetic Particle Testing (MT) on the impeller blades, and Radiographic Testing (RT) on the welded areas, to confirm the integrity of the work.

Diffuser Repair

Beyond the blades, the diffuser bearing housing was also repaired. Inspection showed the upper and lower bearing housings to be neither concentric with each other nor square to the axial face. The repair ran through rebushing the bearing housing, centring the diffuser, grinding the OD, and fitting a rubber bearing. 3D scanning was carried out before and after the work to confirm geometric accuracy.

Lower Shaft Repair

On the lower shaft, the OD at the impeller position was found to be oval and bent. To bring the shaft back to operational requirements, the impeller area was machined to the target drawing, and the upper shaft position and coupling hub ID were polished. Besides the impeller, diffuser, and shaft, the work also covered the repair of several of the CWP's main supporting components.

On the guide vane the work covered:

• Welding
• Fitting stiffeners
• Grinding
• NDT PT & MT

On the stage case the work covered:

• Spot welding
• Machining
• NDT PT & MT

Precision Repair in Support of CWP Reliability

This repair of Circulating Water Pump inspection findings demonstrates SSMN's ability to handle large, critical components through a combination of welding repair, machining, dimensional correction, centring, coating, and Non-Destructive Testing. By integrating inspection, repair, machining, welding, dimensional verification, and NDT, SSMN is committed to delivering precise repair solutions that support the readiness and reliability of generating equipment. Through its experience across turbomachinery and rotating equipment components, SSMN continues to strengthen its role as a trusted partner in maintenance, repair, and engineering services, supporting the continuity of industrial and power generation operations in Indonesia.